Driving under unfamiliar conditions, such as unfamiliar traffic system and unfamiliar vehicle configuration during overseas holidays, might cause fatality, injury or property damage. In these cases, a driver needs to apply their prior knowledge to a new driving situation in order to drive safely. This ability is called cognitive flexibility. Prior research has found that left/mixed-handed people show superior cognitive flexibility in tasks required such ability than right-handed people. This paper aims to explore the relationships among cognitive flexibility, handedness and the types of errors drivers make, specifically at roundabouts and intersections in an unfamiliar driving condition. We conducted an experiment using a right-hand driving simulator and a left-hand simulated traffic scenario as a driving condition to collect the related data to driving at roundabout and intersection. All participants were not familiar with that condition. We found that left/mixed-handed drivers show a significantly superior cognitive flexibility at a turn-left roundabout and intersection. Also left/mixed handed drivers make a significantly fewer number of errors than right-handed drivers when entering the roundabout and approaching the intersection.